Bearing



w. HEER BEARING June 15, 1965 5 Sheets-Sheet 1 Filed 001;. 26, 1961INVEN 1 OR.

WALTER HEER BY z Attorneys w. HEERQ June 15, 1965' BEARING 5Sheets-Sheet 2 Filed 001:. 26, 1961 W. HEER BEARING June 15, 1965 FiledOct. 26, 1961 3 Sheets-Sheet 3 INVENTOR.

WALTER HEER 1- i ill.

Attorneys United States Patent Of 3=,l&9,389 Patented June 15, 1965 ice3,189,389 BEARING Walter Heer, Zurich, Switzerland, assignor to EscherWyss Aktiengesellschaft, Zurich, Switzerland, a corporation ofSwitzerland Filed Get. 26, 1961, Ser. No. 147,919 Claims priority,application Switzerland, Nov. 10, 1960, 12,551/60 8 Claims. (Cl. 308-9)This invention relates to a bearing for a shaft and the application ofthis bearing to the spindle of a machine tool, more particularly. alathe.

.In order to obtain high machining accuracy, efforts are made in machinetools to avoid as far as possible deformations of the individual partsunder the applied loads. Lathe spindles, for example are therefore madeas resistant to bending as possible.

Heretofore, however, too little attention has been paid to the fact thatany spindle, even though made with a relatively large diameter, bends onthe application of a load. It has been shown that when heavy workpiecesare mounted on a spindle, the latter, may set itself appreciablyobliquely in its bearings as shown in FIG. 1 with reference to theexample of a lathe spindle. Here, 1 denotes the spindle which is carriedin bearings 2 of the headstock. The spindle 1 bends, due to the load Pon the spindle end. At points A and B, therefore, it bears withincreased pressure against the bearing surfaces.

Metallic contact of the spindle with the hearing at the particularpoints may give rise not only to operating troubles, but also increasedbearing wear at these points, so that even a straight spindle no longerrests uniformly in the bearing. a

In the mounting of a shaft, the present invention obviates thesedisadvantages by the fact that the shaft is freely adjustable in itsinclination in the hearing when deflected by the applied load.

The invention will be described having reference to the accompanyingdrawings in which:

FIG. 1 is a schematic showing illustrative of the hearing problemssolved by applicant,

FIGS. 2 to 8 represent in simplified fashion constructional examples ofthe subject of the invention as applied to the mounting of amachine-tool spindle,

FIG. 2 is an axial section of one embodiment of the invention,

FIG. 3 is an axial section of a modification of the invention,

FIG. 4 one of the bearings of the constructional form according to FIG.2 in elevation on a larger scale,

FIG. 5 a section on the line VV of FIG. 4, 7

FIG. 6 the other bearing of the constructional form according to FIG. 3,in elevation on a larger scale,

FIG. '7 a section on the line VIIVII of FIG. 6, and

FIG. 8 a section on the line VIII-VIII of FIG. 6;

According to FIGS. 2 to 8, the horizontal-axis spindle .12 of a lathe ismounted in two radial bearings 13 and 14 having bearing bushes 15 and 16of adjustable inclination. The bearing bush 15 of the bearing 13 has inaddition bearing faces 17 and 18 extending on both the end surfaces 17and 18 of the bearing bush 15 so ends in planes at right-angles to thespindle axis for resurface 17, and in the case of the other surface toprotion of the spindle in this plane. Only one of the pivots 22 is shownin the drawing. The other would besituated symmetrically thereto withrespect to the vertical plane passing through the spindle axis.

The projections 21 of the bearing bush 15 are provided on theirunderside with recesses of approximately semicircular cross-seotion, inwhich the upper halves. of the pivots 22 engage. The lower halves of thepivots 22 rest in recesses of approximately semicircular cross-sectionof a fixed bearing member 23 of the headstock.

The pivot 22 is provided with a vertical bore 24, through which passeswith clearance a bolt 25 screwed into the fixed bearing member 23. Thebolt 25 also passes through the projection 21 of the bearing bush 15. Onthe upper end of the bolt is a nut 26, which presses this projection 21against the pivot 22, but only so stronglythat in operation, the bearingbush 15 canw not be lifted upwardly.

The slender bolt 25 is so little resistant to bending that in theangular range coming into consideration, it offers no appreciableresistance to rotation of the bearing bush about the axis of the pivot22. To permit such rotation, a clearance 27 is also provided between theprojection 21 of the bearing bush 15 and the supporting element 23. i

The surfaces 17, 18 of the axial bearing act at the same time as controlsurfaces for automatic adjustment of the bearing bush 15 according tothe inclination of the spindle. 12. If this inclines for exampledownwardly on the left of the bearing 13 (FIG. 2), the ring 19 will bepressed more strongly on the lower side against the surface 17 of thebearing bush 15 than on the upper side. A torque will thus be exerted onthe bearing bush 15 in respect of the axes of the pivots 22 andwilladjust the bearing bush in accordance with the inclination of thespindle. The ring 21! co-operating with the face 18 acts in acorresponding manner. 1 Advantageously, hydrostatic bearings of a kindknown per se will be used. Accordingly, the bearing surface of thebearing bush 15 is provided with pockets 28 distributed on the peripheryand forming liquid pads by means of lubricant supplied under pressure.Each of these pockets is supplied with lubricant by means of a separatepump 29 in accordance with FIG. 2, delivering a definite quantity ofliquid to the respective pockets.

A particular advantage is obtained by providingalso the end surfaces 17and 13 of the bearing bush 15 with individual pockets 30 and 3 1,respectively, distributed on the periphery and supplied with lubricantunder pressure by separate pumps 32 and 33 (FIG. 2), thus forming liquidpads, against which bear the rings 19 and 20 of the spindle 12. Therings 19 and 20 co-operate with as to form throttling gaps for thedischarge of pressure lubricant from the pockets 3t and 31. This notonly results in a small friction loss at the surfaces 17 and 18, but bysuitably arranging the lubricant supply, it is also possible to preventwith certainty metallic contact of the surfaces 17 and 13 with the rings19 and 20. Since the pressure in the pockets varies very considerablywith variation in the width of the discharge gap between theco-operating surfaces, considerable adjusting forces are immediatelyproduced with slight inclination of the spindle 12 to the bearing bush15, so that friction in the pivots 22 is easily overcome. i

It may also suflice to provide a number of pockets on only one of thesurfaces 17 or 18, for example in the vide only a single annular pocket.

In the case of bearing 14, substantially the same device is provided forpermitting adjustability as in the case of bearing 12. According toFIGS. 6 and 7, the bearing bush 16' is provided laterally withprojections 34 which rest rotatably on horizontal-axis pivots 35 atright-angles to the spindle axis. The pivots 35 lie with their lowerhalves in corresponding recesses of a fixed bearing member 36 of theheadstock. A bolt 37 with nut 38 and passing with clearance through thepivot 35 is again used for fixing the bearing bush.

The radial bearing 14 is also constructed as hydrostatic bearing.Accordingly, the sliding surface of the bearing bush 16 is provided witha number of pockets 3% distributed on the periphery and supplied withlubricant in the same way as the pockets 28 of the bearing bush by meansof separate pumps 49 (FIG. 3).

Since, in these pockets, the pressure of the lubricant is practicallyconstant over the entire length axially, the liquid pads in the case ofinclination of the spindle 12, are unable to exert a torque on thehearing bush 16. In an axial extension 41 of the bearing bush 16,therefore, a separate cylindrical control surface 42 is provided, whichsurrounds the spindle 12; with approximately the same clearance as thebearing bush 16 itself. This surface 42 is provided with two pockets 43which again, as is known in the case of hydrostatic bearings, are soprovided with lubricant that in each pocket, a pressure is adjustedwhich is dependent on the gap width between control surface 42 andspindle 12. For this purpose, separate pumps 44 are connected to thepockets 43, each of which pumps supplies under pressure the samequantity of lubricant to the corresponding pocket.

The pockets 43 are offset in the axial direction of the spindle 12 by anamount a (FIG. 6) relatively to the pivots 35, so that the pressure ofthe lubricant in the pockets 43 exerts a torque on the bearing bush 116.One of the two pockets 43 is ituated above and the other below (FIG. 6).,If the spindle 12 is central in the control surface 42, the dischargegaps for the two pockets are equal in size. The same pressure is thusadjusted in both pockets, and since the pocket are diametricallyopposite, the forces exerted by the lubricant pressure on the projection41 of the bearing bush cancel each other.

If, on the contrary, due to a deflection of the spindle 12, the partco-operating with the control surface 42 moves upwardly, the dischargegap of the upper pocket 43 will become smaller and that of the lowerpocket 43 larger. The lubricant pressure therefore increases in theupper pocket and decreases in the lower pocket. Equilibrium isdisturbed. The forces exerted on the projection 41 of the bearing brush16 give an upwardly directed resultant which with regard to the pivotsexerts a torque on the bearing bush 16 in the clockwise direction. Thebearing bush therefore turns in the same direction of rotation on thepivots 35 until it has reached the same inclination as the spindle andthe condition of equilibrium is re-established by centering of thecontrol surface 42 with respect to the spindle 42.

In the present case, in which only one possibility of pivoting of thebearing bush 16 about the horizontal axis is provided, the two pockets43 shown in the control surface 4-2 are sufficient. In the case ofpivotability in all directions, at least three pockets uniformlydistributed on the periphery and supplied with pressure liquid wouldhave to be provided in the control surface.

Instead of the cylindrical surface 42, without departing from theprinciple of the invention, for the co-operation of the bush 16 with thespindle 12, any other surface of revolution with inclination withrespect to the spindle axis could also be provided, the pockets thenbeing disposed offset in the tangential direction of said surface ofrevolution relatively to the pivot axis of the bearing bush, so that thepressure in the pockets exerts a torque on the bearing bush turningabout the pivot axis.

Apart from spindles for machine tools, the mounting described may alsobe used for other shafts which have to adapt themselves to theparticular load in operation, for example for the shaft of a Peltonturbine loaded by the jet pressure Which is variable during operation.

'What is claimed is:

1. In a bearing of a machine tool in combination a fixed bearing member;a bearing bush mounted pivotally in said fixed bearing member so as toallow angular displacement about an axis extending at right-angles tothe axis of the bearing bush; a spindle mounted for rotation in saidbush; said bush having end faces extending at righ -angles to thespindle axis and each end face having pockets with separate pressurelubricant supply means; and said spindle being provided with shoulders.co-operating with said end faces of the bearing bush so as to define athrottling gap for the discharge of the pressure lubricant from saidpockets. 7

2. In a bearing of a machine tool in combination a fixed bearing member;a bearing bush mounted pivotally in said fixed bearing member so as toallow angular displacement about an axis extending at right-angles tothe axis of the bearing bush; a spindle mounted for rotation in saidbush; said spindle and said bearing bush having cylindrical surfaces ofrevolution co-operating with one another; said surface of revolution ofthe bush being formed in axial extensions of the bearing bush and beingprovided with pockets opening toward said surface of revolution of thespindle and having separate pressure lubricant supply means, saidsurfaces of revolution defining a throttling gap for the discharge ofthe pressure lubricant of said pockets.

3. In combination a fixed bearing member, a bearing bush pivotallymounted in said fixed bearing member so as to allow angular displacementabout an axis perpendicular to the axis of the bearing bush, said bushhaving a cylindrical bearing surface to support transverse load in theregion of the pivot axis of the bush; a spindle mounted for rotation insaid bush; at least one extension of the bearing bush axially spacedfrom said pivot axis and formed with a first control surface; a secondcontrol surface carried by the spindle and coacting with the firstcontrol surface to define therebetween a gap, the first control surfacebeing provided with at least two pressure fluid containing pocketsopening toward the second control surface; and separate pressure fluidsupply means connected to each of said pockets, said pockets beingdisposed so that fluid pressure variation resulting from variations inthe width of said gap produces the torques necessary for automaticallyaligning the axis of the p-ivotally mounted bearing bush with the axisof the spindle.

The combination defined in claim 3 in which the control surfaces arecylindrical and coaxial with the spindle.

5. The combination defined in claim 4 in which the extension of the bushwhich forms the first control surface consists of diametricallyoppositely arranged axial projections of the bearing bush, each beingprovided with a pressure fluid pocket opening toward the surface of thespindle.

6. The combination defined in claim 3 in which the control surfaces areannular and disposed coaxially with and at right angles to the spindleaxis.

7. The combination defined in claim 3 in which the bearing surface forsupporting said transverse load is provided, in the region of the pivotaxis, with an annular series of pressure lubricant pockets so as to forma hydrostatic bearing.

8. In combination a fixed bearing member provided with a pair ofrecesses of about half circular cross-section; a bearing bush; a pair oflateral projections carried by said bearing bush and having thereinrecesses of about half circular cross-section and arranged in opposingrelation to the recesses in the fixed bearing member; cylindrical ivotsengaged between said opposed recesses, and having their axes aligned andperpendicular to the axis of the bearing bush, said bearing bush havinga cylindrical bearing surface to support transverse load in the regionof the pivot axis of the bush; flexible bolts passing with clearancethrough openings in said pivots so as to connect the lateral projectionsWith the fixed bearing member, clearance being left between the lateralprojections and the fixed bearing member to allow pivotal movement ofthe bearing bush; a spindle mounted for rotation in said bush; at leastone extension of the bearing bush axially spaced from said pivot andformed With a first control surface; a second control surface carried bythe spindle and coacting with the first control surface to definetherebetween a gap, the first control surface being provided With atleast two pressure fluid containing pockets opening toward the secondcontrol surface; and separate pressure fluid supply means connected toeach of said pockets, said pockets being disposed so that fluid pressurevariation resulting from variation in the Width of said gap prothe axisof the pivotally mounted bearing bush with the axis of the spindle.

References Cited by the Examiner UNITED STATES PATENTS ROBERT C.RIORDON, Primary Examiner.

duces the torques necessary for automatically realigning 15 FRANK R.SUSKO, Examiner.

1. IN A BEARING OF A MACHINE TOOL IN COMBINATION A FIXED BEARING MEMBER;A BEARING BUSH MOUNTED PIVOTALLY IN SAID FIXED BEARING MEMBER SO AS TOALLOW ANGULAR DISPLACEMENT ABOUT AN AXIS EXTENDING AT RIGHT-ANGLES TOTHE AXIS OF THE BEARING BUSH; A SPINDLE MOUNTED FOR ROTATION IN SAIDBUSH; SAID BUSH HAVING END FACES EXTENDING AT RIGHT-ANGLES TO THESPINDLE AXIS AND EACH END FACE HAV-